Thermostatic control



July 12, 1938. K. w. DU BOIS 2,123,672

THERMOSTATIC CONTROL Filed April 27, 1937 2 Shets-Sheet 1 f mmmuum".

Y INVENTOR a j ffezuzefia WflwBow ORNEY July 12,1938. K. w. DU BOIS THERMOSTATIC CONTROL Filed April 27, 1937 2 Sheets-Sheet 2 Patented July 12, 1938 UNITED STATES PATEN'r orrrca THERMOSTATIC CONTRQL necticut Application April 27,

5 @iaims.

My invention is particularly intended for use with electrically heated brooders for chickens. To maintain a brooder at the proper temperature it is necessary to open and close the heater circuit frequently. For this purpose an electric switch is provided which is actuated in one direc tion by a temperature responsive device such as an expansible and contractible bellows and in the other direction by a spring. It is highly desirable that the action of the switch be adjustable so that the temperature of the brooder may be regulated to the desired degree.

One object therefore of my invention is to provide a device which is sensitive and readily adjustable.

Another object is to provide a construction which is rugged and reliable and not likely to get out of adjustment accidentally.

Another object is to provide a device which is simple and of few parts.

The preferred form of the invention includes a stationary part which constitutes the base or support and an arm hinged to the base. These two parts carry the respective contact points of the switch.

A plate-like spring rests on the arm and is connected at one end by a link to the base and at the other end by a screw to the arm.

This screw coacts with the thermo-responsive member and is adjustable in the arm for regulating the action of the switch arm. The switch contacts may be either of the snap action or ordinary slow break.

Fig. 1 shows a side View of the device installed in a brooder which isv shown in dotted lines. 4

Fig. 2 is a side view and partial section of the device approximately full sized.

Fig. 3 is a transverse section on the plane or the line 3-3 of Fig. 2.

Fig. 4 is a plan view of the device without the thermo-responsive device.

Fig. 5 is a side view of a fragment of the device showing the spring dotted in an alternative position. a

Fig. 6 is a drop-perspective view of the principal parts of the device.

One suitable form of brooder is shown in a copcnding application Serial Number 101,219 filed September 17th, 1936,by me.

In this form the main casing ll! of the brooder has an inner ceiling II and air is drawn in by a fan ill at the top and forced between the casing and the ceiling into the chamber I3 beneath the ceiling where the chicks are housed. A skirt 1937!, Serial No. 139,179

(@11- MiG- 1449) or curtain it depends from the casing. The air is heated by a suitable protected resistance type heater 5% arranged around the inside of the ceiling. The theme-responsive bellows it of conventional form contains a sensitive fluid which expands and contracts with the rise and fall of the temperature in the chamber where the bellows are located.

The base ii of the device is supported by the ceiling through the medium of the tube i3 and the frame 89. The tube is screwed into the base and held by a set nut 28. it extends downward through the ceiling and serves to support the bellows in the proper position in the brooder chamber H3.

The thermostatic switch device may be mounted at an angle as shown or with the tube l8 vertical or in any other suitable position.

lihe stationary contact 23 of the switch which contacts the heater circuit is carried by the circuit terminal 22 which is mounted on the insulating block 23 which is secured on the end of the base remote from the pivot pin 26. lhe switch arm 25 is pivoted on pin E i and carries at its outer end the movable switch contact 26 which is insulated from the arm in any suitable manner and connected by a flexible conducting strip or wire 2? to the circuit terminal 28 mounted on the block 23.

A screw til has a threaded engagementin a passage 3i in arm 25 and at its lower end engages the upper end of the rod 32 which extends downward through the tube i8 and pressesagainst the upper surface of the bellows iii. A plate-like spring 33 rests on a sort of knife edge 3 on .the upper surface of the arm 25. One end of this spring has a threaded portion 35 for the screw and the other end has an opening 36 for the hook 3?! of link 38. The arm 25 has a passage for the link. The base also has a passage lil for the link and a seat or groove H for the foot 62 or" the link. This foot and the groove extend transversely of the base so as to in effect provide a knife-edge bearing against which the tension or" the spring 33 is exerted. The spring is so set as to exert pressure downwardly on the screw 36 and thus hold the arm down with the switch in the closed circuit position.

When the bellows expands with a rise in temperature it raises the arm 25 and opens the circuit which cuts off current through the heater. When the air in the chamber i3 cools the predetermined amount the bellows contracts and the spring 33 moves the arm 25 so as to close the circuit and start up the heating action again. The

ii and in turn supports the bellows a pressure on the bellows can be regulated by adjusting the screw 3b in the arm 25. The spring 33 exerts a constant pressure on the threads of the screw so as to prevent it from turning accidentally. By disconnecting the spring from the hook 371- the spring may be rotated about the screw 39 so as to change its initial position as shown by the dotted lines in Fig. 5.

other end of the springv and actuating means 00- acting with said screw.

2. In a switch, a base, an arm hinged thereto, a pressure screw carried by the arm, a plate-like spring having its central portion supported by the arm, said screw passing through one end of the spring, and a link hinged to the base and to the end of the spring opposite the screw.

3. A thermostatic switch including a base, a stationary switch member thereon, an arm hinged at one end to said base and movable at its other end toward and from the base, a switch member carried by themovable end of said arm, a bellows carried by the base, a movable rod con nected to the bel1ows, a screw fast to the arm and opcratively connected to the rod to move the arm upward away from the base and a pivotally seated spring plate having one end connected to areaeva the base and its other 'end connected to the screw for biasing the arm toward the base.

4. A thermostatic switch including a base, a stationary switch member thereon, an arm hinged at one end to said base and movable at its other end toward and from the base, a switch member carried by the movable end ofsaid arm, a bellows carried by the base, a movable rod connected to the bellows, a screw fast to the arm and operatively connected to the rod to move the arm upward away from the base and a spring plate pivotally mounted at its center on thearm and having one end detachably connected to the base and its other end screw threaded to the screw for adjustment up and down along said screw.

5. A thermostatic switch including a base, a stationary switch member thereon, an arm hinged at one end to said bme and movable at its other end toward and from the base, a switch member carried by the movable end of said arm, means for moving said arm and switch member away from the base, said means including a bellows on the base, a movable rod operatively connected with the bellows and a screw member supported by and extending through the arm and operatively connected to the movable rod, and means for normally biasing said am toward the base, said 'means including a link. member supported by the base and extending loosely through the arm, a spring plate member having one end connected to the link and its other and connected to the screw and a pivotal support for said plate on the arm. KENNETH W. DU B018. 

